Evaporator for refrigerating systems



R.- w. DAVENPORT Oct. 11, 1932. vArpngwqg FOR ngggxgsmvrme s Y $TEMS Re.18,621

Original F1136 April 195'? A TTORNE Y.

Reissue-d Oct.'11, 193a UNITED S ATES PATENT OFFICE N801! W. DAVENPORT,OI DETROIT, MICHIGAN, ASSIGNOB 'IO CHICAGO 'IOOL COMPANY, 01' NEW YORK,N. Y A CORPORATION OF NEW EVAPOBATOB FOB BEFRIGERATING SYSTEMS emu in.1,789,110, dated my 1, 1930, Serial No. mp7s, ma April a, 1027.

filed has 30, 1989;

This invention relates to refrigerating apparatus with particularreference to small mechanically operated refrigerating outfits, such asthose intended for household use, in which it is desirable tofreeze'liquid in a relatively small chamber, while sufficient heat isextracted from a larger chamber in which perishable articles, such asfood may be preserved. More particularly, the invention relates torefrigerating systems of the closed cycle type utllizing as therefrigerant fluid a physical mixture of an evaporable liquid and of agas substantially inert to andinsoluble in the liquid, such as disclosedand claimed in my Patent No. 1,619,194 of March 1st,1927, and operatingin accordance with the process disclosed and claimed in my Patent No.1,619,196 of March 1st, 1927.

One object of the invention is to provide improved means for evaporatinga liquid to effect refrigeration at a plurality of temperatures and at asingle total pressure. An-. other object is to utilize the refrigeratingeffect primarily for freezing. Still another object is to provide asimple and compact evaporator unit adapted to be disposed 1n a foodchamber and to effect freezing of liquids while protecting the foodchamber from the low temperature of the freezing compartment. Otherobjects will be apparent from the detailed description which follows:

Refrigerating systems which operate by straight eva oration, as in thereversed Clausius-Ran 'ne cycle, provide means for extracting heatfromboth the freezing chamber and the refrigerating chamber at the samefreezin temperature. In previous disclosures, suc as my patent aplication No. 105,372 filed April 29th, 1926, have set forth systemsoperating on the vapor-gas principle for evaporating liquids in aplurality of spaced evaporators into one or all of which the gas andvapor mixture ofthe refrigerant is expanded. Such previous arrangementsprovide that the evaporators be spaced late orally or vertically and besurrounded by zones or chambers operating at different temperatures.

The present invention aims toefiect refrigeration inzones operating atdifferent terns Serial N0.v 820,21.

Application ,for refine peratures also but with the distinction that iione zone is inside the other. In the preferred arrangement the colderzone, for freezing water and other liquids, is contained within thehigher temperature zone. In practice at least two evaporators are used,one of the evaporators being at least partly enclosed by the other.Means are provided for causing two evaporators to absorb heat atdifferent temperatures. This may be effected by utillzlng the vapor-gasprinciple and causing the expansion. of the vapor-gas stream into theinner evaporator either solely or primarily.

in which the evaporating means are shown in vertical section, theevaporators in Fi 1 operating partly on the va or-gas princip e andpartly straight-"cycle w ile the evaporators 1n Fig. 2 operate entirelyon the vaporgas principle. 7

The closed cycle systems shown in Figs. 1 and 2 each have a pump orcompressor A and a condenser B, these elements bein of any suitable ordesired type. The fluid withdrawn from the evaporator means by ump A isdischarged into condenser B at higher temperature and pressure where itgives up its heat and the condensed liquid together with the gas andresidual vapor in the system is fed back into one of the evaporatormembers through suitable means for passing both liquid'and gas, such forexample as a Venturi nozzle C or other fixed or variable orifice. Theevaporating units may resemble in exterior configuration theconventional forms of evaporators heretofore used in the conventional orRankine c cle systems.

Evaporator unit 1% in Fig. 1 comprises an inner evaporator 3 arranged tobe at least partly enclosed by additional evaporators 4 and 5. All theevaporators open into a, header 6, the outlet of evaporator 3 being bypreference at a higher level than the outlets of evaporators 4 and 5.Pump A withdraws vapor and gas from header 6 through a connection F, theinletof which is disposed closely adjacent to the bottom of a receptacle7 which may serve as a bafiie plate and catch liquid passing toward thepump. As shown, feeding device C opens into the bottom of evaporator 3which contains liquid refrigerant and" the products of condenser B areexpanded directly thereinto so that this evaporator operates on thevapor-gas principle producing a high absorption of heat from itsimmediate surroundings and creating a freezing zone within evaporator D.The space between .the evaporator may be used to contain receptacles 8for water or other liquids to' be frozen. The whole structure may bemounted in the usual way in the refrigerating chamber of a domesticrefrigerator. Evaporators 4 and 5 also contain refrigerant liquid whichis subjected only to the low pressure produced to pump A so thatevaporation takes place only on the surface of the liquil in these twoevaprorators which surface is in header 6, or adjacent thereto, with theresult that evaporators 4 and 5 operate on the conventional or straightpumping cycle.

With the above arrangement the operation is as follows: Upon startingthe system, the

liquid in receptacles 8 is first frozen into ice by the low temperatureeflect of the inner evaporator 3 before the outer evaporators 4 and 5get very cold, although they are of 'course picking up some heat fromthe refrigerating chamber. After operating for some time the latent heatof freezing is all or nearly all absorbed and the expansion in thecentral evaporator 3 becomes nearly U adiabatic. By t e time that ice isformed the outer evaporators 4 and 5 begin to get cold enough to pick upheat from the refrigerating chamber at a high rate, thereby more rapidlycooling the air therein down to the required temperature. Thus theeffect is to first rapidly freeze the liquid and then cool therefrigerating chamber.

The evaporating means in Fig. 2 comprises a central or inner evaporator9 into which the products of condenser B are discharged through feedingdevice C so that this eva orator operates on the vapor-gas princip e.Instead of discharging into header 10 to which pump A is connected, thepartly expanded gas together with the vapor of the refrigerant liquidreleased in evaporator 9 is arranged to discharge into the enclosingevaporators 12 and 13 as by pipe 11. By preference evaporators 12 and 13are interconnected at the bottom forming in effect a single evaporatorand pipe 11 may lead to the interconnecting portion of evaporators 12and 13.- Outer evaporators 12, 13 are thus in series with evaporator 9and open into header 10 from which leads pipe F to pump hig ertemperature than evaporator 9 in accordance with thedisclosure relativeto differential temperatures in systems operating on the vapor-gasprinciple as set forth in my copending application, Serial No. 77,156,filed December 22, 1925, which issued August v14, 1928, as Patent No.1,680,453.

From the above it will be apparent that the present invention aims toproduce freezing of liquid within the refrigerating chamber whileprotecting the latter agalnst the freezing temperature through theinterposition of an additional evaporator which operates at a highertemperature.

While pre erred forms of the invention have been herein shown anddescribed, it is to be understood that the invention is not limited tothe specific details thereof, but covers all changes, modifications andadaptations within the scope of the appended claims.

I claim as my invention:

1. A refrigerating system of the closed cycle type-operating on thevapor-gas principle havingevaporator means operating at a plurality ofvapor pressures for providing two temperature zones, one of said zonesbeing within the other.

2. A refrigerating system of the closed cycle type operating on thevapor-gas principle having evaporator means operating at a plurality ofvapor pressures for providing a higher temperature zone and a lowertemperature zone, the lower temperature zone being within the highertemperature zone.

3. A refrigerating system having an evaporator unit, a compressor, and acondenser, said parts being connected together to form a closed cyclesystem, said unit comprising an inner evaporator and an outer evaporatorat least partly enclosing said inner evaporator, and means for effectingabsorption of heat by said inner evaporator at a lower temperature thanby said outer evaporator.

4. A refrigerating system having an evaporator unit, a compressor, and acondenser, said parts being connected together to form a closed cyclesystem, said unit comprising an inner evaporator and an outer evaporatorat least partly enclosing said inner evaporator, and means for operatingsaid inner evaporator on the vapor-gas principle and for operating saidouter evaporator at a higher'temperature than said inner evaporator.

5., 'A refrigerating system having an evaporator unit, a compresser, anda condenser, said parts being connected together to form a least part yenclosing said inner evaporator,

' and means for operating both said evaporators on the vapor-gasprinciple but effecting initial expansion of the refrigerant medium in'said inner evaporator.

6. In a refrigerating system the combination with a compressor and acondenser of an evaporator for liquidfmeans to feed liquid and gas fromsaid condenser into said evaporator, a second evaporator partlysurrounding said first evaporator, means to supply liquid to said secondevaporator, and means to conduct vapor from both evaporators to saidcompressor.

7. In a refrigerating system the combination with a compressor and acondenser of an evaporator for liquid, means to feed liquid and gas fromsaid condenser into said evaporator, a second evaporator part1surrounding said first evaporator, a hea er to which said evaporatorsare connected, and means connecting said header and said com pressor.

8. In a refrigerating system the combination with a compressor and acondenser of comprising a an evaporator for liquid, means to feed liquidand gas from said condenser into said evaporator, a second evaporatorpartly surrounding said first evaporator, a header to which saidevaporators are connected, a connection from said header to saidcompressor, and bafiie means in said header adjacent the inlet to saidconnection.

9. An evaporator unit for refrigerating systems operating on thevapor-gas principle comprising a plurality of evaporators, a header towhich said evaporators are connected, and connections whereby one ofsaid evaporators may be operated at a lower temperature than theremaining evaporators.

10. An evaporator unit for refrigerating systems operating on thevapor-gas principle comprising a central evaporator, additionalevaporators atleast partly surrounding said central evaporator, meansinterconnecting said evaporators to permit a Single orators andoperating said-central evaporator at a lower temperature than the otherevaporators.

11. An evaporator unit for refrigerating systems operating on thevapor-gas principle' p urality of evaporators, a header to which saidevaporators are connected, said evaporators being disposed in spacedrelation to permit the placing therebetween of containers for liquids tobe frozen, and connections whereby one of said evaporators may beoperated at a lower temperature than the remainingevaporators.

12. An evaporator unit for refrigerating systems operating on thevapor-gas principlecomprising a central evaporator, additionalevaporators spaced from said central evaporator and at least partlyenclosing the latter, a header for said evaporators, and

means interconnectin said evaporators so that fluid entering said unitpasses upwardly twice before reaching said header. I

13. An evaporator unit for refrigerating systems operating on the vaor-gas principle comprising a plurality o evaporators, a header to whichsaid evaporators are connected, an outlet connection from said header, aliquid collecting baflie within said header .beneath said connections,and an inlet connection to one of said evaporators to cause the same tooperate at a lower temperature than the remainder of said evaporators.

14. An evaporator unit for refrigerating systems operating on thevapor-gas principlecomprising a central evaporator, addi-' tionalevaporators spaced from said central evaporator and at least partlyenclosing the latter, a header for said evaporators, an outletconnection from said header, a liquid collecting bafile in said 'headerbeneath said connection, and means connecting said evaporators in seriesto cause fluid entering said unit to pass upwardly twice in a continuouspath before reaching said header. 15. .In a refrigerating system, anevaporator comprisin a header, means for containing liquid re rigerantconnectedto said header and communicating therewith, said means forminga cooling compartment below said header, another means having apassageway therethrough arranged within said coolin compartment, andmeans for supplying re rigerant to said header through said passageway.16. In a refrigerating system, an evaporator comprising a header, meansfor containing liquid refrigerant connected to said header andcommunicating therewith, said means forming a cooling compartment belowsaid header, another means having a passageway 'therethrough arrangedwithin said cooling compartment, both said means being arrangedto'maintain articles placed in said cooling compartment at substantially afreezing temperature, and means for supplying refrigerant to said headerthrough said passageway.

17. In a refrigerating system the combi nation with a compressor and acondenser of an evaporator for liquid, means to feed refrigerant fromsaid condenser into said evaporator, a second evaporator partlysurrounding said first evaporator, means to supply liquid to said secondevaporator, and means to conduct vapor from both evaporators to saidcompressor.

18. In a refrigerating system the combination with a compressor and acondenser of an evaporator forliquid, means to feed refrigerant fromsaid condenser into said evaporator, a second evaporator partlysurrounding said first evaporatorg a ileader to which I I saidevaporators are connected, and means

